本文選題：瑞利面波勘探 + 裂縫檢測　； 參考：《長江大學(xué)》2014年碩士論文

【摘要】：改革開放以來,隨著國家加大基礎(chǔ)設(shè)施建設(shè)的投入力度,各類大型工程建筑不斷涌現(xiàn),由于現(xiàn)代工程建筑的主要材料是鋼筋混凝土,而混凝土由于受到各種內(nèi)部或外部作用的影響而產(chǎn)生裂縫,進(jìn)而影響混凝土的質(zhì)量,對建筑物造成很大的危害。因此必須對這些裂縫進(jìn)行檢測,掌握裂縫狀況及有關(guān)參數(shù),以判斷裂縫對建筑物的危害程度及研究相應(yīng)的補(bǔ)強(qiáng)措施,挽救人民的生命財(cái)產(chǎn)安全。 混凝土裂縫檢測一直是工程建設(shè)中的技術(shù)難題。由于檢測理論和方法的不足,目前,對深度大的垂直裂縫還沒有一種有效的檢測方法。為了合理評價裂縫對混凝土結(jié)構(gòu)安全性的影響和制定后續(xù)的加固方案,必須準(zhǔn)確確定裂縫的狀態(tài)、發(fā)展趨勢和形成原因。其中以裂縫的深度、長度和寬度作為最重要的三個指標(biāo)。尤其裂縫深度是其中的關(guān)鍵指標(biāo)。在實(shí)際檢測工作中,裂縫深度檢測要比長度和寬度的檢測困難得多。 裂縫寬度檢測分三類：塞尺或裂縫寬度對比卡(用于粗測,精度低)、裂縫顯微鏡(精度在0.02～0.05mm)、裂縫寬度測試儀。目前最主要的方法還是裂縫顯微鏡,但裂縫寬度測試儀發(fā)明后,避免了人工近距離調(diào)節(jié)焦距的要求,降低了勞動強(qiáng)度。 裂縫深度檢測最直接和準(zhǔn)確的方法是鉆孔取樣,但該方法不僅費(fèi)時費(fèi)力,而且對建筑結(jié)構(gòu)有一定的損害,當(dāng)裂縫深度較大或位于特殊部位時,難以進(jìn)行鉆孔取樣。其次是聲波對測法,在平行裂縫的一側(cè)激發(fā)聲波信號,另一側(cè)接收透射的信號,通過比較無裂縫和有裂縫的透射信號或通過透射層析成像來判斷裂縫深度,然而此法很多時候需要在裂縫兩側(cè)鉆孔來布置觀測系統(tǒng),同樣也是有損檢測。 目前更多采用的是無損檢測技術(shù),主要有超聲波法和沖擊彈性波法,這兩種方法都是在混凝土表面布置觀測系統(tǒng),根據(jù)裂縫底端的折射信號的特征和傳播路徑的幾何關(guān)系來推算裂縫的深度。超聲波法通過超聲波探頭激發(fā)和接收信號,超聲信號的頻率高但能量較低,一般適用于淺裂縫的檢測。沖擊彈性波法采用錘擊震源,信號頻率低但能量高,適用于較深裂縫的檢測。但這兩種方法存在的問題是當(dāng)裂縫中存在填充物時,聲波信號大部分能量通過填充物傳遞,裂縫底端的折射信號往往很難判斷,對深裂縫尤其顯著。 近年來,發(fā)展一種新的裂縫無損檢測方法-瑞利面波法,同樣在混凝土表面布置觀測系統(tǒng),采用錘擊震源,通過接收的瑞利面波特征來推算裂縫的深度。超聲波法和沖擊彈性波法是利用彈性波中的體波進(jìn)行檢測,而地表激發(fā)的彈性波中大部分能量為瑞利面波,且在分層介質(zhì)中,瑞利面波具有頻散特性,瑞利面波的波長不同,穿透深度也不同。瑞利面波法具有分辨率高、應(yīng)用范圍廣、受場地影響小、檢測設(shè)備簡單、檢測速度快、經(jīng)濟(jì)等一系列優(yōu)點(diǎn),廣泛應(yīng)用于淺表層巖土工程勘察和災(zāi)害地質(zhì)調(diào)查等領(lǐng)域。 本文簡要回顧了各種傳統(tǒng)物探方法在裂縫檢測中的應(yīng)用以及運(yùn)用瑞利面波對裂縫進(jìn)行無損檢測的事例。引出研究課題-運(yùn)用瑞利面波檢測混凝土的垂直裂縫。在瑞利面波原理介紹部分詳細(xì)介紹了如何運(yùn)用凡友華的無量綱實(shí)數(shù)傳遞矩陣算法對頻散曲線進(jìn)行正演計(jì)算,通過交錯網(wǎng)格有限差分法以及Rune Mittet的自由邊界條件處理和指數(shù)衰減吸收邊界條件處理進(jìn)行數(shù)值模擬。運(yùn)用τ-p變換算法對頻散曲線能量譜進(jìn)行計(jì)算。把模擬后得到的頻散曲線值與實(shí)際理論值作對比。得到此數(shù)值模擬方法的可行性。之后進(jìn)行裂縫介質(zhì)的數(shù)值模擬,分別建立有裂縫與無裂縫的模擬進(jìn)行研究對比,以及建立不同深度的裂縫進(jìn)行研究對比,最后把我們建立的垂直裂縫數(shù)值模擬與三峽大壩實(shí)測數(shù)據(jù)作對比。發(fā)現(xiàn)體波和面波通過裂縫時都會產(chǎn)生反射和透射,反射波比透射波的能量要強(qiáng),并且都會沿裂縫向下傳播,在裂縫端點(diǎn)處產(chǎn)生散射。而且發(fā)現(xiàn)在裂縫介質(zhì)中,面波沒有高階模。需要注意的是如果裂縫是空氣的話,面波和縱波都會有反射和散射,但不會有透射。意味著在實(shí)際檢測中,裂縫的一側(cè)只會接收到散射波。然而瑞利面波檢測混凝土垂直裂縫的理論尚不完善,還有待廣大面波工作者進(jìn)一步的研究。
[Abstract]:Since the reform and opening up, as the state has increased the investment in infrastructure construction, all kinds of large-scale engineering buildings are constantly emerging, because the main material of the modern engineering construction is reinforced concrete, and the concrete is caused by the effects of various internal or external effects, which affect the quality of the concrete and cause a great deal of construction. Therefore, it is necessary to test the cracks, grasp the conditions of the cracks and the related parameters, in order to judge the extent of the damage to the building and to study the corresponding reinforcement measures to save the people's life and property safety.
Concrete crack detection has always been a technical problem in engineering construction. Due to the lack of detection theory and method, there is no effective detection method for deep vertical cracks at present. In order to evaluate the effect of cracks on the safety of concrete structure and formulate a subsequent consolidation scheme, it is necessary to determine the state of the crack accurately. The depth, length and width of the cracks are the three most important indicators. Especially the depth of the crack is the key index. In the actual testing, the detection of the depth of the crack is much more difficult than the length and width.
Crack width detection is divided into three categories: tape gauge or crack width contrast card (used for coarse measurement, low precision), fracture microscope (precision in 0.02 to 0.05mm), crack width tester. The most important method is crack microscope at present, but after the invention of crack width tester, it avoids the requirement of the close range adjustment focal length and reduces the labor intensity.
The most direct and accurate method for detecting crack depth is drilling sampling, but the method is not only time-consuming and hard to take, but also has certain damage to the structure of the building. When the depth of the crack is large or in the special part, it is difficult to carry out the drilling sampling. Secondly, the acoustic wave is used to measure the sound wave signal on one side of the parallel crack and the other side receives the transmission letter. The fracture depth is judged by comparing transmission signals without cracks and cracks or through transmission tomography. However, this method needs to be drilled on both sides of the crack to arrange the observation system in many cases, and it is also a damage detection.
At present, more use is nondestructive testing technology, mainly ultrasonic wave method and shock elastic wave method. These two methods all arrange observation system on the surface of concrete. According to the characteristics of the refraction signal at the bottom of the crack and the geometric relation of the propagation path, the ultrasonic wave method excite and receive the signal through the ultrasonic probe. Sound signals have high frequency but low energy, which are generally applicable to the detection of shallow cracks. Shock elastic wave method adopts a hammer shock source, which is low in frequency but high in energy, and is suitable for detection of deep cracks. However, the problem of these two methods is that when there are fillers in the crack, most of the energy of acoustic signals is passed through the filling material and the end of the crack is at the end of the crack. Refraction signals are often difficult to judge, especially for deep fractures.
In recent years, a new nondestructive testing method, Rayleigh surface wave method, is developed, which is also arranged on the surface of concrete. By hammering the source, the depth of the crack is calculated by the characteristics of the Rayleigh wave received. The ultrasonic wave method and the impact elastic wave method are detected by the body wave in the elastic wave, while the elastic wave excited by the surface is large. Partial energy is Rayleigh surface wave, and in stratified medium, Rayleigh surface wave has frequency dispersion characteristics, Rayleigh surface wave has different wavelengths and penetration depth. Rayleigh surface wave method has a series of advantages, such as high resolution, wide application range, small influence of site, simple detection equipment, rapid detection speed, and a series of advantages, which are widely used in shallow surface geotechnical engineering exploration. Inspection and disaster geological survey and other fields.
This paper briefly reviews the application of various traditional geophysical methods to crack detection and the application of Rayleigh surface wave to nondestructive testing of cracks. The research topic - the use of Rayleigh surface wave to detect the vertical cracks in concrete. The application of van Eila's dimensionless real number transfer moment in the Rayleigh wave principle is introduced in detail. The dispersion curve is forward calculated by the array algorithm, and the numerical simulation is carried out by the staggered grid finite difference method, the free boundary condition treatment of Rune Mittet and the exponential attenuation absorption boundary condition. The energy spectrum of the dispersion curve is calculated by the algorithm of the tau -p transformation. The calculated dispersion curve values are compared with the actual theoretical values. The numerical simulation of the fractured medium is carried out after the numerical simulation of the fractured medium, the comparison of the crack and the non crack simulation, and the comparison of the cracks in different depths are compared. Finally, the numerical simulation of vertical cracks and the measured data of the Three Gorges dam are compared. The surface waves are reflected and transmitted through cracks. The energy of the reflected Bobbi transmission wave is strong, and it will propagate down the crack and scatter at the end of the crack. And it is found that there is no high order mode in the fractured medium. It is important to note that if the crack is air, both the surface wave and the longitudinal wave will reflect and scatter, but not the surface wave and the longitudinal wave, but not the surface wave and the longitudinal wave. There is transmission. It means that in actual detection, only the scattering waves will be received on one side of the crack. However, the theory of vertical crack detection of concrete by Rayleigh surface wave is not perfect, and it is still to be further studied by the broad face wave workers.

【學(xué)位授予單位】：長江大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TU755.7

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